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Tuesday, July 13, 2010

Why Paul The Prognosticating Octopus Pesters Me

Ahhhh....we can all breathe a collective sigh of relief now that the World Cup is over.  The soccer football lovers are no longer anxious and missing work watching games at 930am. The soccer haters can be happy they no longer have to hear about Ronaldinho, Xavi, Bafana Bafana, Vuvuzela, pitches, kits, Jabulani balls and other such inanity. And everyone else can just let out a big sigh, because it helps you feel better and surely  the World Cup is stressing you out.

But the thing I can't get over is the story of the octopus in Germany who 'predicted' the correct winner of 7 games featuring Germany and the final between Spain and the Netherlands.  He has been called Paul the Psychic Octopus but since he really can't read people's minds (like a psychic), most reputable news outlets switched to the somewhat more accurate 'prognosticating' octopus.

The frustrating thing for me is how often prognostication in medicine gets brushed aside because of the inherent uncertainty as GS noted in the comments in a recent post:
When I meet skepticism about the accuracy of an unfavorable life expectancy prognosis, it often takes the form of "but only God knows that". Any attempts at correction of the misconception at that point can only be interpreted as an affront to God. Unfortunately, accurate understanding of prognosis is a prerequisite to realistic goal setting and optimal decision making.
I will agree with anyone about the uncertainty but it does not mean that prognostic estimates may have no basis in reality and should not be helpful in decision making.  So why does the octopus bother me?  Because this light hearted story talked about over and over again reinforces mathematical illiteracy (aka innumeracy).  In general people do not understand statistics and how to evaluate risk, and all too often statistics are blown off if they don't agree with one's world view (the lies, damn lies, and statistics).

But in medical decision making, the understanding of risks and percentages is key for good informed consent.  Which is why in many family meetings palliative medicine and hospice teams will spend time on conversations like this: [word choice adjusted for brevity here, NOT an actual verbatim conversation]
  • Family member: "Do you think she will die?"
  • Health Care Provider: "Yes, it looks like she will die."
  • Family member: "But there is always a chance she could pull through?"
So the next time you work through these very difficult but important conversations think about all the influences in the world that help reinforce innumeracy:
So if one looks at Paul and sees that he predicted the correct winner in 8 out of 8 games it looks like it was a 1/256 or 0.3% chance for him to be correct right? (Do you know how I got those numbers? I hope so!)

But if we look at the games only two matches of 8 did the lower FIFA ranked team win (Serbia #15 over Germany #5 and Uruguay #16 over Germany #5).  So using the Clever Hans trick this doesn't seem like such an amazing trick if most of the time the handlers went with the favored team (also the home team).  The other thing the media does not report is the potential other 'predictors' who were wrong, so we only hear about the 'amazing' story, just like patients and families hear about 'miracle cures' with herbs, and the one guy who was in a coma for 2 weeks and he is walking around today at work.  Those 'amazing' stories get repeated and present a skewed understanding of probabilities.

(H/T to PZ Meyers for confirming my frustrations)

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